| 摘要 |
<p>PURPOSE: To reduce block distortion by evaluating the mutual error between partial differentiations at boundaries calculated from respective blocks and determining the value of quantization so as to minimize errors of the partial differentiations. CONSTITUTION: Boundary conditions are considered at the boundary of a left quantized picture element block 10, an upper quantized picture element block 11 and a picture element block 12 to be quantized and the partial differentiation at the respective boundaries is calculated from the respective block by using the same components of the blocks 10, 11 and 12 for the partial differentiation at the boundaries of the blocks 10, 11 and 12. The value r (w, v) of the candidate of the quantization is calculated from a quantization table Q (w, v) and the picture element block S (w, v) to be quantized. Then, the X/Y-direction partial derivative vector of the boundary is calculated by a prescribed arithmetic operation, the error (d) of the partial differentiation is obtained and the value of the quantization is decided so as to minimize the error (d). Thus, the block distortion generated by image compressions reduced.</p> |
